The present invention relates generally to magnetoresistive (MR) heads for use in disc drive data storage systems. More particularly, the present invention relates to an MR head having separate permanent magnet (PM) layers for stabilization of the MR sensor layer and the soft adjacent layer (SAL).
In order to provide the required head performance in magnetic recording applications, it is desirable to stabilize the MR element (MRE) or sensor layer into a single magnetic domain. Stabilization of the MRE layer into a single domain is typically achieved by the use of combinations of sensor geometry, anti-ferromagnetic layers, PM magnetostatic coupling layers, or PM ferromagnetic coupling layers. In designs using a SAL for vertical bias, both the SAL and the MR layer of the MR head should be stabilized into single domain states for optimal head performance.
In PM overlaid designs, the SAL and MRE layer are both ferromagnetically coupled to the PM layer. However, in these PM overlaid designs, the head resistance is large since no low resistivity layers can be used without affecting head stability. This is due to the fact that both the MR sensor layer and the SAL must be in contact with the PM for stabilization. Consequently, a low resistance MR head utilizing SAL and overlaid PM stabilization would be a significant improvement in the art.